Cameras are sometimes utilized in high-temperature environments. As one example, infrared imaging cameras are used by firemen in burning buildings. Typically, a fireman takes such a camera into a burning building and uses it to look for thermal patterns that indicate the presence of a person, a hot spot which may be the source of the fire, or some other thermal characteristic of interest.
Early infrared-imaging cameras were fairly large and complex. The incoming infrared radiation typically passed through a rotating perforated disk called a “chopper” in order to facilitate its detection by a detector. Further, these prior cameras needed active cooling systems, typically based on thermoelectric cooling (TEC) devices, in order to maintain the lenses and/or detector at temperatures facilitating accurate and reliable operation.
More recently, infrared detectors have been developed that are capable of operation without certain support structure, such as choppers and active cooling systems. Eliminating support structure of this type is advantageous, because it reduces the size, weight, cost and power consumption of the camera. However, eliminating active cooling arrangements may lead to undesirable thermal activity within the camera that may affect its operation. For example, when a firefighter is in a very high temperature environment for approximately five minutes and then returns to a cooler environment, a circular shape may appear in the viewing screen that obscures the view for two or more minutes, which could be very dangerous to the firefighter.